(1) Field of the Invention
The invention relates to a stabilizer with the features of the preamble of claim 1.
(2) Description of Related Art including information disclosed under 37 CFR 1.97 and 1.98.
Such stabilizers are employed in motor vehicle technology.
In principle a stabilizer working according to the torsion bar principle is coordinated to each axle of a motor vehicle, wherein the stabilizer runs parallel to the axle and is attached at two ends at a wheel suspension. These stabilizers have the task to prevent or, respectively, diminish the transfer of rolling motions caused by the road situation and starting at the wheels onto the vehicle. Such rolling motions are generated mainly in the curves of the road or at the unevenness of the road, such as for example potholes or ruts.
Single part stabilizers exist, which are constructed in their dimensioning and in their material properties such that they receive torsion forces of a predetermined order of magnitude and that they can furnish corresponding counter forces. Single part stabilizers react however to different loads either too soft or too hard, which is disadvantageous for the driving comfort and single part stabilizers cannot accept increased loads.
Therefore increasingly two part stabilizers are employed, wherein the two part stabilizers are connected to each other by an axially fixed and rotary elastical clutch. Such a clutch is shown for example in the German printed patent DE 43 42 360 C2, wherein a rubber spring element is interposed between the two stabilizer parts. This rubber spring elements exhibits a softer spring constant and the thereby increases the possible twist angle between the two stabilizers. This way larger road loads can be opposed. The twist angle however is insufficient in case of road unevenness problems acting extremely different onto the wheels, such as they occur cross-country. In addition a slippage exists between the two stabilizer parts because of the rubber spring element, which operates disadvantageously onto the driving behavior in case of a straight driving and planar road.
Increasingly two part stabilizers with a switchable clutch are employed for such extreme load situations, such as there are described for example in the German printed patent document DE 19705809 A1. This coupling is furnished as a friction clutch and is controlled hydraulically depending on the load of the wheels. The two halves of the clutch are frictionally engaged connected in case of a high outer load and are separated in case of a lacking load. A slippage occurs between the two stabilizer halves upon a small load of the wheels. Such friction clutches are not safe, since also a slippage of the clutch cannot be excluded in the closed position and since an unlimited twist angle is possible in the separated position under an exclusion of the stabilizer function. This is a safety risk.
There exists no switchable clutch in all known constructions, which connects the two stabilizer halves without play in the block condition and which safely separates the two stabilizer halves in the released condition and which admits only a limited twist angle of as desired plus/minus 40 degrees in the released state.